Various display devices are equipped for both mono and stereo viewing. Unlike mono viewing, stereo viewing involves the display of separate content for the right and left human eye. Specifically, such stereo viewing requires the presentation of a separate image to the left and right human eye. In one particular type of stereo viewing, namely time sequential stereo, such left and right images are presented in an alternating manner. To ensure a proper stereo viewing experience, alternating shutter glasses are also typically used which make the left image visible to the left eye and the right image to the right eye at the appropriate time.
In the past, time sequential stereo viewing has worked well on CRTs and related displays [e.g. high frame rate (DLP) projectors, etc.]. However, time sequential stereo viewing has not shown promise with liquid crystal displays (LCDs), whether flat-panel or in the form of a projector, due to several issues. For example, a slow response time of pixels in LCD environments causes ‘ghosting’ of the left image in the right view, and visa versa. Still yet, the nature of the LCD update process unfortunately results in only short periods of time when the right image and left image may be present in their entirety, as will now be described in more detail.
FIG. 1A illustrates hypothetical shortcomings that would exist if stereo viewing were attempted utilizing an LCD. As shown in the present hypothetical example, the LCD would receive pixels in raster scan order (i.e. left to right, line by line from top to bottom, etc.) over a cable 10, such as a digital video interface (DVI) or video graphics array (VGA) cable. A first left image L1 intended for viewing by a left eye is sent over the cable 10 first. Thereafter, there is a pause in transmission called the vertical blanking interval VBI. Next, a first right image R1 intended for the right eye is sent, and so forth.
Unlike CRTs and other related displays, LCD pixels have individual capacitive storage elements that cause each pixel to retain its color and intensity until it is updated by LCD driver-related electronics, which addresses pixels in raster order. Thus, at time T1, when part of the first right image R1 has been sent, the actual image emitted from the LCD screen includes the ‘not yet overwritten’ (e.g. red) part of first left image L1 at the bottom, and the newly written (e.g. green) part of the first right image R1. Further, at T2, and, in fact, for the entire vertical blanking interval VBI starting at time T2, the display includes only the first right image R1. At time T3, the first right image R1 has been partially overwritten by a second left image L2, in the manner shown. To this end, if the display content at time T1 and T3 were shown to the left or right eye, such eye would unfortunately receive content, at least in part, not intended for such eye.
As mentioned earlier, stereo glasses equipped with right and left eye shutters are often employed to ensure that the proper eye views the appropriate image, during stereo viewing. As shown, in the present hypothetical example, after the first left image L1 is displayed, a left eye shutter control 20 switches the left shutter to an open orientation (during which a right shutter is maintained in a closed orientation). Similarly, after the first right image R1 is displayed, a right eye shutter control 30 switches the right shutter to an open orientation (at which time the left shutter toggles to and is maintained in a closed orientation).
Again, each eye unfortunately, receives content, at least in part, not intended for such eye for a sizeable portion of the duration in which the associated shutter is in the open orientation, resulting in unacceptable stereo viewing. There is thus a need for overcoming these and/or other problems associated with the prior art.